CN110366451B

CN110366451B - particle separation

Info

Publication number: CN110366451B
Application number: CN201780087173.3A
Authority: CN
Inventors: V·什科利尼科夫; 陈健华
Original assignee: Hewlett Packard Development Co LP
Current assignee: Hewlett Packard Development Co LP
Priority date: 2017-04-23
Filing date: 2017-04-23
Publication date: 2021-07-30
Anticipated expiration: 2037-04-23
Also published as: WO2018199874A1; KR102264614B1; JP2020507468A; BR112019017671A2; US11325125B2; EP3558540A4; CN110366451A; US20210213451A1; KR20190105637A; EP3558540A1; JP6992079B2

Abstract

The fluid-entrained particle separator may include an inlet channel for guiding fluid-entrained particles, a first separation channel branching off the inlet channel, a second separation channel branching off the inlet channel, and a medium for generating a medium acting on the particles. The electric field of the electrophoretic force to guide the particles to the electrodes of the first separation channel or the second separation channel, wherein the first separation channel, the second separation channel, the electric field, and the dielectrophoretic force extend in a plane.

Description

Particle separation

Background

The separation of particles is carried out in various industries. For example, in biology and medicine, rare cells are often isolated from a patient's blood for diagnosis. The isolation of particles such as rare blood cells presents a number of challenges.

Drawings

FIG. 1 is a schematic illustration of a portion of an exemplary fluid entrained particle separator;

FIG. 2 is a flow diagram of an exemplary method for separating fluid-entrained particles;

FIG. 3 is a schematic illustration of a portion of another exemplary fluid entrained particle separator;

FIG. 4 is a schematic illustration of a portion of yet another exemplary fluid entrained particle separator;

FIG. 5 is a schematic illustration of a portion of yet another exemplary fluid entrained particle separator;

FIG. 6 is a cross-sectional view of the fluid entrained particle separator of FIG. 5 taken along line 6-6;

FIG. 7 is a cross-sectional view of the fluid entrained particle separator of FIG. 5 taken along line 7-7;

FIG. 8 is a schematic illustration of a portion of another exemplary fluid entrained particle separator;

FIG. 9 is a cross-sectional view of the fluid entrained particle separator of FIG. 8 taken along line 9-9;

FIG. 10 is a cross-sectional view of the fluid entrained particle separator of FIG. 8 taken along line 10-10;

FIG. 11 is a cross-sectional view of another exemplary fluid entrained particle separator taken along line 11-11 of FIG. 8;

FIG. 12 is a cross-sectional view of the fluid entrained particle separator of FIG. 11 taken along line 12-12 of FIG. 8;

FIG. 13 is a schematic illustration of a portion of yet another exemplary fluid entrained particle separator;

FIG. 14 is a cross-sectional view of the fluid entrained particle separator of FIG. 13 taken along line 14-14;

FIG. 15 is a cross-sectional view of the fluid entrained particle separator of FIG. 13 taken along line 15-15;

FIG. 16 is a flow diagram of an exemplary method for forming a fluid entrained particle separator;

FIG. 17 is a top perspective view of a portion of another exemplary fluid entrained particle separator;

FIG. 18 is a top view of the fluid entrained particle separator of FIG. 17;

FIG. 19 is a graph illustrating dielectrophoretic forces generated in a portion of the fluid-entrained particle separator of FIG. 18;

FIG. 20 is a top view schematically illustrating another exemplary fluid-entrained particle separator;

FIG. 21 is a top view schematically illustrating yet another exemplary fluid-entrained particle separator.

Throughout the drawings, identical reference numbers designate similar, but not necessarily identical, elements. The figures are not necessarily to scale and the dimensions of some portions may be exaggerated to more clearly illustrate the illustrated examples. Moreover, the figures provide examples and/or embodiments consistent with the description; however, the description is not limited to the examples and/or embodiments provided in the drawings.

Detailed Description

An exemplary particle separator for separating particles (e.g., biological cells) based on the size and electrical susceptibility of the particles relative to each other and/or the surrounding medium is disclosed herein. The particle polarization characteristics are a function of the frequency of the applied electric field. Since the frequency of the electric field can be easily modified, such a particle separator is highly adaptable and applicable to a wide range of particles and applications.

The example particle separators disclosed herein have geometries and architectures that facilitate a uniform force field. The result is improved reproducibility and reliability of particle separation. The disclosed particle separator may further position particles within the stream at predictable locations within the generated hydrodynamic field. The result is that the particles can be reproducibly and reliably separated and directed to two different areas or two different separation channels to achieve consistent results.

Exemplary fluid entrained particle separators disclosed herein use dielectrophoretic forces to facilitate separation of different particles. The separated fluid particles are entrained in the fluid directed through the inlet passage. The electrodes create an electric field that exerts dielectrophoretic forces on the particles to guide the particles from the inlet channel to the different separation channels.

In some embodiments, the particles entrained in the fluid are collected into a laminar flow within the inlet channel prior to separation using a particle collector. In one embodiment, the particle collector may comprise a hydrodynamic collector that utilizes first and second sheath flows of buffer solution that sandwich a solution containing particles to provide such laminar flow. In other embodiments, other particle collectors may be employed, such as a free-flow negative dielectrophoresis particle collector and a free-flow isotachophoresis particle collector.

In one embodiment, the separation channel and the electrodes are positioned and oriented such that the electric field generated by the electrodes and the resulting dielectrophoretic forces extend in a single plane with the separation channel. Because the separation channel, electric field, and dielectrophoretic forces extend in a single plane, the separation of particles is more predictable and less chaotic, leading to more reliable results.

An example fluid-entrained particle separator is disclosed herein that may include an inlet channel for directing particles entrained in a fluid, a first separation channel branching off from the inlet channel, a second separation channel branching off from the inlet channel, and electrodes for creating an electric field that exerts a dielectrophoretic force on the particles. Dielectrophoretic forces direct particles to the first separation channel or the second separation channel. The first separation channel, the second separation channel, the electric field and the dielectrophoretic force extend in one plane.

An exemplary method for separating particles entrained in a fluid is disclosed herein. The method may include directing particles entrained in the flow through the inlet passage. The method may further comprise applying an electric field in a plane to the stream to exert dielectrophoretic forces in the plane on the particles to transfer a first subset of the particles in the stream to a first separation channel extending in the plane and a second subset of the particles in the stream to a second separation channel extending in the plane.

An example method for forming a fluid entrained particle separator is disclosed herein. The method may include forming an inlet channel, a first separation channel branching from the inlet channel, and a second separation channel branching from the inlet channel. Electrodes are formed on side surfaces of the first separation channel and the second separation channel. The electrodes are electrically isolated on side surfaces opposite to each other.

FIG. 1 is a schematic diagram illustrating portions of an exemplary fluid entrained particle separator 20. Separator 20 includes inlet channel 24, separation channel 26, separation channel 36, and

electrodes

40A, 40B, and 40C (collectively electrodes 40). The inlet channel 24 comprises a channel, e.g. a microfluidic channel, which guides a solution containing the particles to be separated.

Separation channels

26 and 36 comprise channels, such as microfluidic channels, extending from inlet channel 24 and branching off from inlet channel 24. The

separation channels

26, 36 lead to different destinations where the separated particles or cells can be collected and analyzed. In some embodiments, particles directed to separation channel 26 or directed to separation channel 36 may be further separated downstream. In the example shown, the

separation channels

26, 36 extend in a single plane, such as a single horizontal plane. In some embodiments, the

separation channels

26, 36 extend in the same plane as the inlet channel 24. Although the

passages

26, 36 are shown as branching off from the inlet passage 24 at an angle of 135 deg., it should be understood that the

passages

26 and 36 may extend from the inlet passage 24 at other angles.

Electrodes 40 are provided to create an electric field across

channels

24, 26 and 36. The electrodes 40 extend in a single plane such that they generate an electric field that extends in the same plane as the plane of the

channels

24, 26 and 36. Because the separation channel, electric field, and dielectrophoretic forces extend in a single plane, the separation of particles is more predictable and less chaotic, leading to more reliable results.

In the example shown, the electrodes 40A extend along the

channels

24 and 26. Electrodes 40B extend along

channels

24 and 36. Electrodes 40C extend along

channels

26 and 36. It will be appreciated that each electrode 40 may be a continuous electrode or may be formed from a plurality of individual elements connected to ground or to a current source (e.g. an alternating frequency current source).

In one embodiment, the

electrodes

40A and 40B are separated by a distance across the inlet channel 24 that is at least 10 times the diameter of the target particles to be separated. Likewise,

electrodes

40A and 40C and

electrodes

40B and 40C are also separated across

separation channels

26 and 36, respectively, by a distance that is at least 10 times the diameter of the target particle being separated. This separation reduces the likelihood that the global electric field will not be significantly distorted by the presence of the particles, thereby similarly separating all particles in the stream.

FIG. 2 is a flow diagram of an exemplary method 100 for separating fluid-entrained particles. The method 100 provides particle separation in a more predictable and less messy manner, thereby producing more reliable results. Although the method 100 is described as being performed with the separator 20, it should be understood that the method 100 may be performed with any of the separators described below or other similar particle separators.

As indicated by block 106, the particles to be separated are entrained in the flow and directed through the inlet passage 24. These particles may be mixed with other particles. For example, certain target particles to be isolated, such as rare biological cells, may be mixed with other biological cells or other particles. As will be described below, in some embodiments, the particles may be collected before or within the inlet channel 24 prior to separation. In one embodiment, the particles may be collected into a laminar flow through the inlet channel 24. In one embodiment, the particles may be collected with a hydrodynamic collector that sandwiches the fluid-entrained particles between a sheet flow of at least one buffer solution. In other embodiments, the fluid-entrained particles may be agglomerated in other ways.

As shown in block 108, the electrode 40 applies an electric field in one plane to the flow of fluid-entrained particles. In one embodiment, an alternating current of a predetermined frequency is applied to the electrodes 40. In one embodiment, the frequency of the alternating current applied to the electrodes 40 is between 20kHz and 200kHz, typically 60 kHz. The electric field exerts dielectrophoretic forces on the particles in a plane which is the same plane in which the inlet channel 24 and

separation channels

26, 36 extend and in which the electric field extends. Particles are separated based on their different responses to dielectrophoretic forces (as a result of their size and difference in electrical susceptibility). The dielectrophoretic forces transfer a first subset of the particles in the flow into a first separation channel 26 extending in the plane and transfer a second subset of the particles in the flow into a second separation channel 36 extending in the plane.

FIG. 3 is a schematic view of another exemplary fluid entrained particle separator 220. The separator 220 is similar to the separator 20 described above, except that the separator 220 additionally includes a particle collector 222. Those remaining components of separator 220 that correspond to components of separator 20 are similarly numbered.

The particle collector 222 collects fluid-entrained particles prior to or within the inlet channel 24 prior to separation. In one embodiment, the collector 222 collects the particles into a laminar flow through the inlet channel 24. In one embodiment, the collector 222 comprises a hydrodynamic collector that sandwiches the fluid-entrained particles between sheath flows (sheath flows) of at least one buffer solution. In other embodiments, the collector 222 may comprise other particle collectors, such as a free-flow negative dielectrophoresis particle collector or a free-flow isotachophoresis particle collector. In other embodiments, the fluid-entrained particles may be agglomerated in other ways. The aggregation of the fluid containing the particles to be separated enhances the separation performance of the separator 220. However, in some embodiments, such particle agglomeration may be omitted.

FIG. 4 is a schematic view of yet another exemplary fluid-entrained particle concentrator 320. The particle collector 320 is similar to the collector 220, except that the

separation channels

26, 36 comprise primary separation channels and the particle collector 320 additionally comprises

secondary separation channels

328, 329, 338, 339 and

electrodes

340A, 340B (collectively referred to as electrodes 340). Those remaining components in the aggregator 320 that correspond to components of the aggregator 220 are similarly numbered.

The

secondary separation channels

328, 329 comprise channels, such as microfluidic channels extending and branching from the primary separation channel 26. The

separation channels

328, 329 lead to different destinations where separated particles or cells can be collected and analyzed. In the example shown, the

separation channels

328, 329 extend in a single plane, such as a single horizontal plane. In some embodiments,

separation channels

328, 329 extend in the same plane as separation channel 26. While the

passages

328, 329 are shown as branching off the separation channel 26 at an angle of 135 °, it should be understood that the

passages

328, 329 may extend at other angles from the separation channel 26.

The

secondary separation channels

338, 339 include channels, such as microfluidic channels, that extend and branch from the primary separation channel 28. The

separation channels

338, 339 lead to different destinations where separated particles or cells can be collected and analyzed. In the example shown, the

separation channels

338, 339 extend in a single plane, such as a single horizontal plane. In some embodiments, the

separation channels

338, 339 extend in the same plane as the separation channel 28. Although the

channels

338, 339 are shown as branching off the separation channel 28 at an angle of 135 °, it should be understood that the

channels

338, 339 may extend from the separation channel 28 at other angles.

Electrodes 340 are provided to establish an electric field that creates the

secondary separation channels

328, 329, 338, 339. The electrodes 340 extend in a single plane such that the electric field they generate extends in the same plane as the planes of the

channels

24, 26 and 36 and the

channels

328, 329, 338, 339. Because the separation channel, electric field, and dielectrophoretic forces extend in a single plane, the separation of particles is more predictable and less chaotic, leading to more reliable results.

In the example shown, the electrodes 340A extend along the

channels

328, 329. The electrode 340B extends along the

channels

338, 339. Electrode 340A cooperates with electrode 40A to establish an electric field across secondary separation channel 328. Electrode 340A cooperates with electrode 40C to establish a field across secondary separation channel 329. Electrode 340B cooperates with electrode 40C to establish a field across secondary separation channel 338. Electrode 340B cooperates with electrode 40B to establish an electric field across secondary separation channel 339. It should be understood that each of the

electrodes

40B and 40C may be a continuous electrode or may be formed from a plurality of individual elements connected to ground or to a current source (e.g., an alternating frequency current source).

In one embodiment,

electrodes

340A and 40A are separated by a distance across secondary separation channel 328 that is at least 10 times the diameter of the target particle to be separated. Likewise,

electrodes

340A and 40C,

electrodes

340B and 40C, and

electrodes

340B and 40B are also separated by a distance across

separation channels

329, 338, and 339, respectively, that is at least 10 times the diameter of the one or more target particles. This separation reduces the likelihood that the global electric field will not be significantly distorted by the presence of the particles, thereby similarly separating all particles in the stream.

The particle collector 320 performs multi-stage particle separation. In the example shown, a laminar flow of fluid containing particles to be separated is directed along the inlet channel 24. The electric field extending across channel 24 and

channels

26 and 28 creates dielectrophoretic forces that differentially direct different particles based on differences in particle size and electrical polarity. The differential response of the different particles to the dielectrophoretic forces causes the laminar flow of the fluid to split, with a first portion of the particles being diverted along the separation channel 26 and a second portion of the particles being diverted along the separation channel 28. Thereafter, the electric field created across

channels

328 and 329 generates dielectrophoretic forces that, based on differences in particle size and electrical polarity, interact differentially with different particles within separation channel 26 to further disrupt the flow of particles within separation channel 26 such that the first portion is further diverted along separation channel 328 and the second portion is further diverted along separation channel 329.

Likewise, creating an electric field across

channels

338 and 339 creates a dielectrophoretic force that differentially directs different particles within separation channel 28 based on differences in particle size and electrical polarity to further disrupt the flow of particles within separation channel 28 such that a first portion is further diverted along separation channel 338 and a second portion is further diverted along separation channel 339. As a result, the original stream of fluid-entrained particles is separated into four distinct sets or groups of particles. Each particle group having particles of similar size and/or electrical polarity. Each particle group has particles that are of a different size or have a different electrical polarity than the particles of the other groups.

Fig. 5-7 illustrate yet another exemplary fluid entrained particle separator 420. Fig. 6 is a cross-sectional view of separator 420 taken along line 6-6 of fig. 5. Fig. 7 is a cross-sectional view taken along line 7-7 of fig. 5. Particle separator 420 includes substrate 422, dielectric layer 423, inlet channel 424,

primary separation channels

426, 428,

electrodes

440A, 440B, and 440C, particles 222 (as described above), and cover layer 450.

Substrate 422 includes at least one layer of material having a series of connected branch recesses 452 formed therein, branch recesses 452 partially forming

channels

424, 426 and 428. In one embodiment, the recess 452 is formed by embossing or molding a material layer forming the substrate 422. In another embodiment, the recesses 452 are formed by cutting, ablating, etching, or other material removal process performed on one or more layers of material forming the substrate 422. In another embodiment, the recess 452 is formed by selective deposition, such as a printing or additive manufacturing process, on a base layer or platform.

In the example shown, the substrate 422 comprises a material having an impedance that is less than or not sufficiently greater than the impedance of the flow of fluid particles to be directed through these

channels

424, 426, 428. In one embodiment, the substrate 422 comprises a material having a resistance of less than 10,000 ohm-centimeters. In one embodiment, the substrate 822 comprises a silicon material having a resistance of less than 10,000 ohm-centimeters.

The dielectric layer 423 includes a layer of material formed on or coating the bottom and opposing sidewalls of the recess 452. The dielectric layer 423 is formed of a material that enables an electric field to pass through and across the fluid within the

channels

424, 426, 428 without passing through the substrate 422, and is of sufficient thickness to achieve this effect. In one embodiment, the dielectric layer 423 is formed of a material having sufficient dielectric properties and is sized such that the impedance of the path through the layer 423 is at a level of at least five times the impedance of the path of the fluid through the

channels

424, 426, 428. In one embodiment, layer 423 is formed of a material having sufficient dielectric properties and is sized such that the impedance of the path through layer 423 is at a level of at least 10 times the impedance of the path of the fluid through

channels

424, 426, 428. In one embodiment, layer 423 is formed from a material having a resistance of at least 10,000 ohm-centimeters. In one embodiment, layer 423 is formed of a material such as silicon nitride or silicon dioxide. In other embodiments, layer 423 may be formed of other materials with sufficient resistance.

Electrodes 440 are provided to create an electric field across

channels

424, 426, and 428. The electrodes 440 extend in a single plane such that they generate an electric field that extends in the same plane as the planes of the

channels

424, 426 and 428. Since the separation channel, electric field, and dielectrophoretic forces extend in a single plane, the separation of particles is more predictable and less chaotic, resulting in more reliable results.

In the example shown, electrodes 440A extend along

channels

424 and 426. Electrode 440B extends along

channels

424 and 428. Electrode 440C extends along

channels

426 and 428. Each of the electrodes 440 is connected to a source of electrical charge, such as an alternating current source having a predetermined frequency based on the polarization characteristics of the particles to be separated.

In one embodiment,

electrodes

440A and 440B are separated by a distance across inlet channel 424 that is at least 10 times the diameter of the target particles to be separated. Likewise, electrodes 440A and 440C, and electrodes 440B and 440C are also separated across

separation channels

428 and 426, respectively, by a distance that is at least 10 times the diameter of the target particle being separated. This separation reduces the likelihood that the global electric field will not be significantly distorted by the presence of the particles, thereby similarly separating all particles in the stream.

In one embodiment, the electrode 440 is formed over the dielectric layer 423 on the side surfaces of the grooves 452, without extending over the bottom of the grooves 452. In one embodiment, the electrode 440 is formed using directional sputtering or angled sputtering that deposits conductive material on the layer 423 on the sides of the groove 452 with no or minimal deposition on the bottom of such groove 425. In other embodiments, the conductive material forming the electrode 440 may be deposited on the layer 423 on the bottom of the recess 452, wherein the conductive material deposited on the layer 423 on the bottom of the recess 452 is subsequently removed while leaving the conductive material on the sides to form the electrode 440.

The

channels

424, 426 and 428 are completed by forming or providing a cover layer or plate 450. In such an embodiment, the impedance of the cover plate 450 is also greater than the impedance of the flow of fluid particles to be directed through these

channels

424, 426, 428, such that the electric field created by the electrodes 440 will pass through the flow of fluid particles rather than through the roof provided by the cover plate 450. In one embodiment, the cover plate 450 is formed from a material having a resistance of at least 10,000 ohm-centimeters. In one embodiment, cover plate 450 is formed from a material such as glass, silicon nitride, or silicon dioxide. In other embodiments, the cover plate 450 may be formed of other materials having sufficient resistance.

Fig. 8-10 illustrate a separator 520, which is another example of a separator 420 formed according to various exemplary methods. Fig. 8 is a top view of separator 520. FIG. 9 is a cross-sectional view of separator 520 taken along line 9-9. Separator 520 is similar to separator 420 except that separator 520 includes a substrate 522 instead of substrate 422 and omits dielectric layer 523. Those remaining components of particle separator 520 that correspond to components of particle separator 420 are similarly numbered.

Substrate 522 is similar to substrate 422 in that a recess 452 is also formed in substrate 522, recess 452 defining

channels

424, 426 and 428. Unlike substrate 422, however, substrate 522 is formed of a material having sufficient dielectric properties and is dimensioned such that the impedance of the path through substrate 522 is at a level of at least five times the impedance of the path of fluid through

channels

424, 426 and 428. In one embodiment, substrate 522 is formed of a material having sufficient dielectric properties and is sized such that the impedance of the path through substrate 522 is at a level of at least 10 times the impedance of the path of the fluid through

channels

424, 426 and 428. In one embodiment, the substrate 522 is formed of a material having a resistance of at least 10,000 ohm-centimeters. In one embodiment, substrate 522 is formed of a material such as silicon nitride, silicon dioxide, or glass. In other embodiments, substrate 522 may be formed of other materials having sufficient resistance. Due to the high impedance provided by the substrate 522, the dielectric layer 423 is omitted, wherein the electrode 440 is formed directly on the material of the substrate 522 along the sides of the recess 452. In one embodiment, the electrode 440 is formed using directional sputtering or angled sputtering that deposits conductive material on the sides of the

channels

424, 426, and 428 with no or minimal deposition on the bottoms of these channels. In other embodiments, the conductive material forming electrode 440 may be deposited on the bottoms of

channels

424, 426, and 428, wherein the material on the bottoms of these channels is subsequently removed. The

channels

424, 426 and 428 are completed by forming or providing a cover layer or plate 450 as described above.

Fig. 8, 11, and 12 illustrate another exemplary fluid entrained particle separator 620. FIG. 11 is a cross-sectional view of separator 620 taken along line 11-11. Fig. 12 is a cross-sectional view taken along line 12-12. Separator 620 is similar to separator 520 described above, except that separator 620 includes substrate 622 and additionally includes bottom layer 650. Those remaining components of splitter 620 that correspond to components of splitter 520 are similarly numbered.

Substrate 622 is similar to substrate 522 except that instead of having recesses 452 extending into substrate 622 and at least partially defining

channels

424, 426 and 428, substrate 622 has a series of through slots 623 that are connected and branch off, extending completely through substrate 622. In one embodiment, the through slot 623 is formed through the substrate 622 by a material removal process, such as etching, ablation, or cutting, performed on the substrate 622. In other embodiments, the slots 623 may be formed during molding or additive manufacturing/printing of the substrate 622. Because substrate 622 does not form the bottom of

vias

424, 426, and 428, substrate 622 is formed from a greater variety or range of materials having a resistance that is less than the resistance of substrate 522.

The bottom layer 650 includes a layer or plate bonded to the substrate 622 opposite the cover layer 450. As with the cover layer 450, the impedance of the bottom layer 650 is greater than the impedance of the flow of fluid particles to be directed through these

channels

424, 426, 428, such that the electric field generated by the electrode 440 will pass through the flow of fluid particles and not through the bottom provided by the bottom layer 650. In one embodiment, the bottom layer 650 is formed of a material having a resistance of at least 10,000 ohm-centimeters. In one embodiment, the bottom layer 650 is formed of a material such as glass, silicon nitride, or silicon dioxide. In other embodiments, the floor layer 650 may be formed of other materials having sufficient resistance.

In one embodiment, a bottom layer 650 is laminated or otherwise bonded to the substrate 622 after the

channels

424, 426, and 428 have been formed through the substrate 622 and after the electrodes 440 have been formed along the sides of the slots 623. In other embodiments, the substrate 622 is formed on the substrate layer 650 before the grooves 623 are formed in the substrate 622. The

channels

Fig. 13-15 illustrate yet another exemplary fluid entrained particle separator 720. Separator 720 is similar to separator 620, except that separator 720 includes a substrate 722 that also forms electrode 440. Fig. 13 is a top view of the decoupler 720. FIG. 14 is a cross-sectional view of one example of the separator 720 taken along line 14-14 of FIG. 13. Fig. 15 is a cross-sectional view taken along line 15-15 of fig. 13. In the example shown in fig. 13-15,

channels

424, 426, and 428 are formed by channels that extend completely through substrate 722, where substrate 722 includes a film or layer of conductive material that also forms electrode 440. As shown in fig. 13, the different electrodes 440 are separated from one another by a gap or opening 725 in the substrate 722, the gap or opening 725 in the substrate 722 being filled with a non-conductive or insulating material 727 such as silicon nitride. In other embodiments, different electrodes 440 may be separated from one another by such gaps or openings 725 that are devoid of material. The cover layer 450 and the bottom layer 650 (as described above) sandwich the substrate 722 therebetween to form the

channels

424, 426, and 428.

FIG. 16 is a flow diagram of another example method 800 for forming a fluid entrained particle separator. As indicated by block 802, an inlet channel, a first separation channel branching from the inlet channel, and a second separation channel branching from the inlet channel are formed. As indicated by block 804, electrodes are formed along side surfaces of the first separation channel and the second separation channel. As indicated by block 806, the electrodes on the opposing side surfaces of the first separation channel and the second separation channel are electrically isolated from each other. The method 800 may be used to form any of the

particle separators

420, 520, 620, and 720 described above.

Fig. 17 and 18 illustrate another example fluid entrained particle separator 820. Fig. 17 is a top perspective view of the particle separator 820. Fig. 18 is a top view of particle separator 820. The particle separator 820 includes a substrate 822, a dielectric layer 823, an inlet channel relating to the bottom,

primary separation channels

826, 828,

secondary separation channels

836, 838,

electrodes

840A, 840B, and 840C, a particle collector 844, and a cover layer 850. The substrate 822 comprises at least one layer of material having a series of connected branch grooves 852 formed therein, the branch grooves 852 partially forming

channels

824, 826, 828, 836, and 838. In one embodiment, grooves 852 are formed by stamping or molding a layer of material forming substrate 822. In another embodiment, the grooves 852 are formed by cutting, ablating, etching, or other material removal processes performed on one or more layers of material forming the substrate 822. In another embodiment, grooves 852 are formed by selective deposition, such as a printing or additive manufacturing process, on a bottom substrate or platform.

In the example shown, the substrate 822 comprises a material having an impedance that is less than or not sufficiently greater than the impedance of the flow of fluid particles to be directed through these

channels

24, 26, 28. In one embodiment, the substrate 822 comprises a material having a resistance of less than 10,000 ohm-centimeters. In one embodiment, substrate 822 comprises a filamentary material having an impedance of less than 10,000 ohm-centimeters.

The dielectric layer 823 includes a layer of material formed on or coating the bottom and opposing sidewalls of the recess 825. The dielectric layer 823 is formed of a material that allows the passage of electric fields through and across the fluid within the

channels

824, 826, 828, 836, 838 without passing through the substrate 822 and is of sufficient thickness to achieve this effect. In one embodiment, dielectric layer 823 is formed of a material having sufficient dielectric properties and is sized such that the impedance of the path through layer 523 is at a level of at least five times the impedance of the path of the fluid through

channels

824, 826, 828, 836, and 838. In one embodiment, layer 523 is formed of a material having sufficient dielectric properties and is sized such that the impedance of the path through layer 823 is at a level of at least 10 times the impedance of the path of the fluid through

channels

824, 826, 828, 836, and 838. In one embodiment, layer 823 is formed of a material having a resistance of at least 10,000 ohm-centimeters. In one embodiment, layer 823 is formed of a material such as silicon nitride or silicon dioxide. In other implementations, the layer 823 may be formed of other materials with sufficient resistance.

Electrodes 840 are provided to generate electric fields across

channels

824, 826, 828, 836, and 838. The electrodes 840 extend in a single plane such that the electric fields they generate extend in the same plane as the planes of the

channels

824, 826, 828, 836 and 838. Because the separation channel, electric field, and dielectrophoretic forces extend in a single plane, the separation of particles is more predictable and less chaotic, leading to more reliable results.

In the example shown, electrodes 840A extend along

channels

824 and 828. Electrodes 840B extend along

channels

824 and 828. Electrodes 840C extend along

channels

826 and 828. It should be understood that each of the electrodes 840 may be a continuous electrode, or may be formed from a plurality of individual elements connected to ground or to a current source (e.g., an alternating frequency current source).

In one embodiment,

electrodes

840A and 840B are separated by a distance across inlet channel 824 that is at least 10 times the diameter of the target particles to be separated. Likewise,

electrodes

840A and 840C, and

electrodes

840B and 840C are also separated across

separation channels

828 and 826, respectively, by a distance that is at least 10 times the diameter of the target particle being separated. This separation reduces the likelihood that the global electric field will not be significantly distorted by the presence of the particles, thereby similarly separating all particles in the stream.

In one embodiment, electrodes 840 are formed over dielectric layer 823 on the side surfaces of grooves 852, without extending over the bottoms of grooves 852. In one embodiment, electrode 840 is formed using directional sputtering or angled sputtering that deposits conductive material on layer 823 on the sides of groove 852 with no or minimal deposition on the bottom of such groove 825. In other embodiments, the conductive material forming electrode 840 may be deposited on layer 823 on the bottom of groove 852, where the conductive material deposited on layer 823 on the bottom of groove 852 is subsequently removed while leaving the conductive material on the sides to form electrode 840.

In other embodiments, the substrate 822 may be formed of a material having an impedance greater than the impedance of the flow of fluid particles to be directed through the

channels

24, 26, 28, such that the electric field created by the electrode 440 will pass through the flow of fluid particles without passing through the substrate 822. In one embodiment, the substrate 822 may be formed of a material having a resistance of at least 10,000 ohm-centimeters. In one embodiment, the substrate 822 is formed of a material such as glass, silicon nitride, or silicon dioxide. In other embodiments, substrate 822 may be formed of other materials with sufficient resistance. In such embodiments, dielectric layer 823 may be omitted, where substrate 822 forms the bottom of

channels

824, 826, 828, 836, 838, and where electrodes 840 are formed directly on the sides of grooves 852, directly on substrate 822.

In other embodiments, particle separator 820 may have an architecture similar to that described above with respect to

particle separator

620 or 720 and may be formed in a manner similar to that described above with respect to

particle separator

620 or 720. In such embodiments, the

channels

824, 826, 828, 836, 838 are defined or formed by through slots in the substrate, rather than grooves, with the bottom layer underlying the substrate and forming the bottom of the channels.

The particle collector 844 is similar to the particle collector 222 described above, except that the particle collector 844 is specifically shown as a hydrodynamic collector. The particle collector 844 includes a sheath flow channel 870, a sheath flow channel 872 and a particle flow channel 874. The

sheath flow channels

870, 872 extend on opposite sides of the particle flow channel 874 and direct a laminar flow of buffer solution that sandwiches a supply of fluid-entrained particles (e.g., a flow of blood) to concentrate the fluid-entrained particle flow therebetween into a laminar flow. The laminar flow of the fluid entrained particle stream helps to better control the subsequent separation of different particles from the stream. Each of

channels

870, 872, and 874 converge at inlet channel 824.

In other embodiments, the particle collector 844 can include other types of particle collectors. For example, the particle collector 844 can include a free-flow negative dielectrophoresis particle collector and a free-flow isotachophoresis particle collector. In some embodiments, the particle collector 844 can be omitted.

In operation, a flow of fluid containing particles to be separated is supplied to the passage 874 through the inlet 875. Similarly, streams of buffer solution are provided to

channels

870, 872 through

inputs

871 and 873, respectively. The flow of buffer solution forms a sheet flow that sandwiches the fluid flow containing the portion to be separated, forming a laminar flow through the inlet channel 824. In one embodiment, the buffer solution in each

sheath flow channel

870, 872 is supplied at a rate greater than the supply rate of the solution containing the cells to be separated. In one embodiment, the buffer solution is supplied at a rate of 0.2mL per minute, while the solution stream containing the portion to be separated is supplied at a rate of 0.2 mL/minute.

Electrodes

840A and 840B have different potentials to form an electric field across inlet channel 824. In one embodiment, electrode 840A is grounded, while electrode 840B has a positive charge. The electric field generates dielectrophoretic forces. Figure 19 is a graph illustrating the dielectrophoretic forces generated. Due to the difference in size and electrical susceptibility, a first fraction or portion of particles having a first size and/or first electrical susceptibility are urged toward separation channel 828 within inlet channel 824, while a second fraction or portion of particles having a second size and/or second electrical susceptibility different than the size/electrical susceptibility of the first fraction of particles are urged toward separation channel 826. The separated particles delivered to separation channel 828 are directed to outlet 880.

The separated particles directed to separation channel 826 are further separated by dielectrophoretic forces generated by the electric field generated by

electrodes

840B and 840C. In one embodiment, when electrode 840B is positively charged, electrode 840C is negatively charged. Due to the differences in size and electrical susceptibility, a first fraction or portion of particles having a first size and/or first electrical susceptibility are urged toward separation channel 836 within separation channel 826, while a second fraction or portion of particles having a second size and/or second electrical susceptibility different from the size/electrical susceptibility of the first fraction of particles are urged toward separation channel 838. The separated particles delivered to the separation channel 836 are directed to the outlet 882. The separated particles deflected to the separation channel 838 are directed to an outlet 884.

FIG. 20 is a top view of another exemplary fluid entrained particle separator 920. Separator 920 is similar to separator 820, except that separator 920 includes three separation channels, i.e.,

channels

926, 928, and 930, extending from inlet channel 824, and includes four electrodes, i.e.,

electrodes

940A, 940B, 940C, and 940C (collectively electrodes 940) for reading different charges.

Channels

824, 926, 928 and 930 have a similar structure to

channels

824, 826 and 828. In one limitation,

such channels

824, 926, 928 and 930 are formed by grooves formed in the substrate, wherein the bottom and sides of the grooves are coated or otherwise covered with a dielectric layer, similar to dielectric layer 423 described above, and wherein electrodes 940 are formed on the sidewalls of the channels, but do not extend over the bottom of the channels. In other embodiments where the substrate has sufficient impedance, the dielectric layer between the substrate and the electrode may be omitted, similar to the impedance of substrate 522 described above.

In operation, a flow of solution containing particles to be separated is collected by the particle collector 844 and directed to the inlet channel 824. The electric field created by

electrodes

940A and 940B across channel 824 creates a dielectrophoretic force that differentially interacts with differently sized particles or particles having different electrical polarizabilities to direct the particles to separation channel 926, separation channel 928, or separation channel 930. In some embodiments, such a separation channel may include additional secondary separation channels and electrodes as described above.

FIG. 21 is a top view of another exemplary fluid entrained particle separator 1020. Separator 1020 is similar to separator 920 except that separator 1020 additionally includes a cylinder or post 1087. Those remaining components of separator 1020 that correspond to components of separator 920 are similarly numbered.

Post 1087 extends at the junction of

channels

824, 926, 928 and 930. The struts 1087 prevent a flow of solution or particles directly across the junction from the inlet channel 824 to the separation channel 930. The struts 1087 reduce the likelihood that particles will enter the separation channel 930 due to the momentum of the solution flowing through the inlet channel 824, rather than due to the size or electrical susceptibility of the particles.

Although the present disclosure has been described with reference to exemplary embodiments, workers skilled in the art will recognize that changes may be made in form and detail without departing from the spirit and scope of the claimed subject matter. For example, while various exemplary embodiments may have been described as including one or more features providing one or more benefits, it is contemplated that the described features may be interchanged with one another or alternatively be combined with one another in the described exemplary embodiments or in other alternative embodiments. Because the technology of the present disclosure is relatively complex, not all variations of the technology are foreseeable. The present disclosure described with reference to the exemplary embodiments and set forth in the following claims is manifestly intended to be as broad as possible. For example, unless specifically stated otherwise, claims reciting a single particular element also encompass a plurality of such particular elements. The terms "first," "second," "third," and the like in the claims merely distinguish between different elements and are not specifically associated with a particular order or particular designation of elements in the disclosure unless otherwise indicated.

Claims

1. A fluid entrained particle separator comprising:

an inlet channel for guiding particles entrained in the fluid;

a first separation channel branching off from the inlet channel;

a second separation channel branching off from the inlet channel;

a particle aggregator for aggregating the particles into a laminar flow within the inlet channel;

an electrode for creating an electric field that applies a dielectrophoretic force to the particles to guide the particles to the first separation channel or the second separation channel, wherein the first separation channel, the second separation channel , the electric field, and the dielectrophoretic force extend in a plane, and wherein the electrodes include at least a first electrode and a second electrode separated by a distance of at least 10 times the diameter of the particles.

2. The fluid entrained particle separator of claim 1, wherein the particle aggregator comprises a hydrodynamic aggregator.

3. The fluid entrained particle separator of claim 2, wherein the hydrodynamic particle concentrator comprises a first sheath flow channel leading to the inlet channel, a second sheath flow channel leading to the inlet channel, and a particle flow channel leading to the inlet channel for supplying particles between sheath fluid from the first sheath flow channel and the second sheath flow channel.

4. The fluid entrained particle separator of claim 1, wherein the particle aggregator is selected from the group of particle aggregators comprising a free-flow negative dielectrophoresis particle aggregator and a free-flow isotachophoresis particle aggregator.

5. The fluid-entrained particle separator of claim 1, wherein each of the first separation channel and the second separation channel includes opposing sidewalls, and wherein the electrodes have parallel to and along the faces of the opposing side walls.

6. The fluid entrained particle separator of claim 1, further comprising:

a third separation channel branching off from the first separation channel; and

a fourth separation channel branching off from the first separation channel, wherein the electric field exerts a dielectrophoretic force on the particles to guide the particles in the first separation channel to the third separation channel or the the fourth separation channel, wherein the third separation channel and the fourth separation channel extend in the plane.

7. The fluid-entrained particle separator of claim 1, further comprising a third separation channel branching off from the inlet channel and extending in the plane, wherein the electric field applies a dielectrophoretic force to the particles to The particles in the inlet channel are directed to the first separation channel, the second separation channel, or the third separation channel.

8. The fluid-entrained particle separator of claim 1, wherein each of the first separation channel and the second separation channel includes a bottom surface made of a material having an impedance of at least 10,000 ohm-cm form.

9. The fluid entrained particle separator of claim 1, comprising:

a substrate having an impedance of at least 10,000 ohm-cm;

a first layer on the substrate and forming the electrode, wherein the inlet channel, the first separation channel, and the second separation channel are formed in the first layer; and

a second layer over the first layer, wherein the substrate and the second layer form the bottom of each of the inlet channel, the first separation channel, and the second separation channel, respectively and top.

10. The fluid entrained particle separator of claim 1, comprising:

a layer having a resistance of at least 10,000 ohm-cm, the layer forming a channel, the channel forming the inlet channel, the first separation channel, and the second separation channel;

A layer of electrode material on opposing sidewalls of the channel to form the electrode.

11. A method for separating particles entrained in a fluid, the method comprising:

directing particles entrained in the flow through the inlet channel;

agglomerating the particles into a laminar flow within the inlet channel by a particle aggregator;

an electric field in a plane applied to the stream by electrodes to apply a dielectrophoretic force in the plane to the particles to transfer a first subset of the particles in the stream into the plane a first separation channel extending, and a second separation channel extending in the plane to divert a second subset of the particles in the stream,

Wherein, the electrodes include at least a first electrode and a second electrode, and the first electrode and the second electrode are separated by a distance that is at least 10 times the diameter of the particle.

12. The method of claim 11, wherein each of the inlet channel, the first separation channel, and the second separation channel has a bottom and a side wall, wherein the side wall has a surface for forming the application. The electric field is a layer of conductive material of the electrode, and wherein the bottom has an impedance higher than that of the flow.

13. A method for forming a fluid entrained particle separator, the method comprising:

forming an inlet channel, a first separation channel branching off from the inlet channel, and a second separation channel branching off from the inlet channel;

forming a particle agglomerator within the inlet channel to agglomerate the particles into a laminar flow;

forming electrodes along side surfaces of the first separation channel and the second separation channel; and

The electrodes on opposite side surfaces are electrically isolated from each other, wherein the electrodes include at least a first electrode and a second electrode separated by a distance of the At least 10 times the diameter of the particles.